1. Field of Invention
The present invention relates to a semiconductor device. More particularly, the present invention relates to a chip package.
2. Description of Related Art
Recently, with the continuous improvement of the integration of the internal circuit of the integrated circuit (IC) chip, the heat produced by the chip is also increased continuously. For the personal computer, IC chips with high integration, such as the Central Processing Unit or drawing chip, produce a great deal of heat. To allow said IC chip to continue normal operation, the IC chip must be kept under a preferable operating temperature in order to avoid degradation of the performance or damage due to overheating. In other words, with the continuous improvement of the processing speed and the data processing capacity of the IC chip, the heat radiating requirements are also enhanced relatively.
On the other hand, along with the development trend of the semiconductor device towards light, thin, short, and small, a package structure has been developed wherein a cavity is formed on a carrier for accommodating a chip, so as to reduce the profile of the package structure and improve its heat radiating effect and electrical properties.
FIG. 1 is a schematic sectional view of a conventional chip package with a heat spreader. With reference to FIG. 1, the chip package 100 comprises a circuit substrate 110, a chip 120, wires 130, a heat spreader 140, and an encapsulating compound 150. The circuit substrate 110 is disposed on a bonding surface 140a of the heat spreader 140 and has an opening 112 for exposing a portion of the bonding surface 140a. The cavity for accommodating the chip 120 is formed from the opening 112 of the circuit substrate 110 and the bonding surface 140a of the heat spreader 140. The chip 120 is disposed on the bonding surface 140a exposed by the opening 112 and coupled to the contacts on the substrate 110 through a plurality of wires 130.
With reference to FIG. 1 again, the encapsulating compound 150 is disposed on the bonding surface 140a exposed by the opening 120 and covers the chip 120, the wires 130, and a portion of the circuit substrate 110. Moreover, a plurality of solder balls 160 is disposed on the ball pads of the circuit substrate 110 for coupling the chip package 110 to the outside. As described above, a great deal of heat is produced by the chip 120 and the circuit substrate 110 when the chip package 110 is in the state of general operation. Then, the heat is transferred to the heat spreader 140 to achieve the goal of heat radiation.
It should be noted that conventionally the circuit substrate 110 is attached to the heat spreader 140 by direct adhesion, i.e., an adhesion layer 170 is formed between the circuit substrate 110 and the heat spreader 140 for fixing the circuit substrate 110 on the heat spreader 140. However, the circuit substrate 110 is easily warped due to the ambient temperature during processing or during use, so that the circuit substrate 110 cannot be attached to the bonding surface 140a of the heat spreader 140 effectively. Thus, this leads not only to a reduction in the effectiveness of heat radiation for the chip package 100 and lower reliability, but further results in difficulty with the subsequent wire bond or ball mount, thereby affecting the yield of processing.